关键词: 脑缺血; 再灌注; 出血转化; 超微结构; 亚低温

Abstract: Objective To investigate the effect of sub-hypothermia on hemorrhagic transformation and ultra-structure of the rats with cerebral ischemia-reperfusion within or beyond 3 hours-the therapeutic time window, and to study the neuroprotective effect of subhypothermia on cerebral ischemia in rats.Methods Using the intra-luminal suture method, we subjected Sprague-Dawley rats to middle cerebral artery occlusion(MCAO) model and reperfusion 3 hours, 6 hours or 9 hours later, and then the rats were divided into normal temperature group, subhypothermia for 3 hours group and subhypothermia 5 hours group. A group of sham-operated animals without ischemic was used as control. At the 24th hour after ischemia, all rats were killed. Six rats were selected in each group for measuring the amount of bleeding according to the method described by Sumii T et al. Two or 3 rats were selected in each group for observing morphologic changes of endothelial cell, gliacyte, neuron and neuropile in retrochiasmatic cortex ischemic boundary zones by electron microscopy.Results The cerebral injury and hemorrhagic transformation aggravated as the time prolonging after ischemia-reperfusion,subhypothermia should prevent the development of the injury and hemorrhagic transformation. Observation under transmission electron microscopes showed that cerebral ultrastructure of retrochiasmatic cortex ischemic boundary zones was damaged in different degrees in MCAOR groups, and the cerebral ultrastructure injury increased in cortex ischemic boundary zones as the ischemic time prolonging. Subhypothermia could alleviate the nerve cell damage. It showed the most effective in MCAO3hR+HT3h group.Conclusion Subhypothermia has protective effect on brain ultrastructure of rats with cerebralischemia reperfusion injury. It provides ultrastructural foundation for brain functional reconstruction.

Key words: Cerebral; ischemia-reperfusion; Hemorrhagic transformation; Ultrastructure; Subhypothermia